CAPTAIN NOBLE AND MR. F. A. ABEL ON FIRED GUNPOWDER, 225 
Two explosion-vessels, both of the general form shown in the annexed figure, but 
weighing, one, 21,311 , 6 grs. (1381 grms.), with a capacity of 501 '54 grs. (32'50 grins.), 
the other weighing 52,931'6 grs. (3430 grms.), with a capacity of 1833'75 grs. (118*83 
grms.), were prepared. The specific heats of both these vessels were carefully 
determined, and the amount of heat absorbed by the calorimeter for various changes 
of temperature was also carefully determined, and corresponding tables for convenient 
use formed. Thermometers specially made for the purpose and capable of being read 
to 0°'01 F. (0°.0055 C.) were used in these experiments. 
Full details of the determination of the specific heat of the vessels and of the absorp¬ 
tion of the heat by the calorimeter are given in the appendix, pp. 264 to 267. 
To determine the heat generated, a charge of from 150 to 200 grs. (9'72 to 12'96 
grms.) in the smaller cylinder, of 400 grs. (25'92 grms.) in the larger cylinder, was 
carefully weighed and placed in the explosion-vessel. The explosion-vessel was then 
immersed in the water of the calorimeter and the charge fired in the usual way, the 
attached thermometer being read before the explosion, and afterwards continuously 
until the maximum temperature (which was usually reached in about 2 minutes) was 
attained." 
In order to make our new calorimetric determinations as complete as possible, and 
with the view of exhibiting the differences in the heat evolved due to changes in the 
composition of the powder, we have not only found separately the heat given off by 
the three principal powders described in our first memoir, but have added to these 
three other powders differing widely in their composition, viz.: ordinary English 
mining, Curtis and Harvey’s well-known powder No. 6, and Spanish spherical. The 
composition of all these powders has been already given either in the present or in our 
former memoir. But for our present purpose it is convenient to place in juxtaposition 
the composition of these six powders. 
Table IV.—Exhibiting the differences in the composition of the powders experimented 
■with which are described in this memoir. 
Nature of powder. 
Saltpetre. 
Sulphate. 
B 
.2 7B 
*5 '£ 
og 
1 Sulphur. 
Carbon. 
a 
<V 
to 
o 
>-> 
C 
O 
bl) 
i? 
o 
Ash. 
s 
Pebble powder. 
‘7467 
•0009 
•1007 
•1212 
•0042 
•0145 
•0023 
•0095 
R. L. G., W. A. 
•7443 
•0013 
.. 
•1009 
•1240 
•0040 
•0127 
•0022 
•0106 
F. G., W. A. 
•7355 
•0036 
•1002 
■1136 
•0049 
•0257 
•0017 
•0148 
! Curtis and Harvey’s No. 6 . 
•7440 
•0029 
Trace 
•1037 
•1066 
•0052 
•0229 
•0031 
•0117 
Mining powder. 
•6166 
•0012 
•0014 
•1506 
•1793 
•0066 
•0223 
•0059 
•0161 
! Spanish spherical .... 
•7530 
•0027 
•0002 
•1242 
•0865 
•0038 
•0168 
•0063 
•0065 
The decomposition they experienced is exhibited in Tables I.+ and II. of the present 
memoir. 
* It is scarcely necessary to state that the correction for the absorption of heat by the calorimeter and 
the effect of cooling was in all cases made. t See also Tables XII. and XIIT. 
MDCCCLXXX. 2 G 
